The invention relates to a long range nozzle, in particular for cooling the strand and/or the supporting and guiding rollers in continuous casting plants by means of jets of liquid or jets of liquid and gas.
In the German Offenlegungsschrift No. 2,208,928 there is described a continuous casting plant for slabs comprising a water-cooled mold, from which the strand is withdrawn continuously, a supporting and guiding zone having rollers between which the strand is guided, and a cooling device having nozzles through which cooling water is sprayed onto the strand and the rollers. The cooling water is supplied by means of flat-section jet nozzles running parallel to the surface of the strand, i.e. to the broad side of the siab, at a distance from the strand surface. The longitudinal axes of the nozzles run parallel to the roller axes. Particularly in continuous casting plants of this type, there is a problem with constructing the flat-section jet nozzles in such a way that far-reaching closely bundled jets are formed with which optionally either the strand surface or the supporting and guiding rollers are acted upon, or with which scale and slag particles can be blown off from the lower side of the slabs.
It is the object of the present invention to provide a long-range nozzle which has various constructional and dimensional features coordinated in such a way that an optimum effect is achieved. The combination of features according to the invention by means of which this object is achieved comprises designing the nozzle to have a plurality, preferably 3 to 10, of parallel nozzle channels arranged side by side in one plane an connecting all of the nozzle channels with each other in the area of the mouth of the nozzle by means of a transverse channel that is open in spraying direction. The transverse channel has limiting areas running parallel to the plane of of the nozzle channels. The hydraulic diameter of each channel is between 1.5 and 4 mm and the ratio of the hydraulic diameter of each channel to the distance between the two channel axes is 0.7 to 0.9.
Preferably the parallel channels of the nozzle are in the form of a line of cylindrical bores with gradually decreasing diameter for the bores closer to the center of the line.
According to a preferred embodiment the water supply is in form of a circular bore and is arranged perpendicular to the plane of the channels and to the annular clearance, so that both the inlet openings and the outlet openings of the channels lie along circular arcs.
A further dimensional feature which is of importance for the close bundling of the jet involves having the ratio of the distance of the parallel limiting areas of the transverse channel to the biggest diameter of the nozzle channels in the range of 1.0 to 1.1.